Molecular Mechanisms Regulating Pancreatic Delta Cell Function and Dysfunction

调节胰腺 Delta 细胞功能和功能障碍的分子机制

• 批准号: 10597228
• 负责人: David Aaron Jacobson
• 金额: $ 44.96万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10597228
• 关键词: Ablation; Amino Acids; Animal Disease Models; Calcium-Sensing Receptors; Cell physiology; Cells; Coupled; Cytoplasm; Data; Diabetes Mellitus; Disease; Dominant-Negative Mutation; Endoplasmic Reticulum; Functional disorder; G alpha q Protein; G-Protein-Coupled Receptors; Glucagon; Glucose; Goals; Homeostasis; Hormone secretion; Human; Insulin; Islets of Langerhans; Knowledge; Laboratory Finding; Mediating; Medical; Membrane Potentials; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Pancreas; Pancreatic delta Cell; Pathogenesis; Pathway interactions; Patients; Physiological; Population; Potassium Channel; Receptor Signaling; Research; Research Project Grants; Role; Signal Transduction; Somatostatin; Stress; Testing; Transgenic Mice; blood glucose regulation; diabetes pathogenesis; diabetic; driving force; experimental study; gain of function mutation; insight; insulin secretion; islet; knock-down; maturity onset diabetes of the young; new therapeutic target; pharmacologic; receptor; response; small hairpin RNA

Project Summary Islet glucose-stimulated somatostatin (Sst) secretion is lost in patients with type-2 diabetes (T2D) and in animal models of the disease, which contributes to disrupted glucagon and insulin secretion. It is generally accepted that Sst secretion from -cells occurs in response to elevated intracellular Ca2+, which primarily results from endoplasmic reticulum (ER) Ca2+ (Ca2+ER) release. However, the mechanisms that control -cell Ca2+ER handling and how they are altered in T2D are largely unknown. Data from our lab finds that the islet-enriched two-pore- domain K+ channel, TALK-1, is an ER localized channel in that provides a countercurrent for -cell Ca2+ER release and Ca2+ER leak. TALK-1-mediated augmentation of the electrochemical driving force for -cell Ca2+ER leak con- strains Ca2+ER storage, which limits glucose-stimulated Ca2+ER release and Sst secretion. Further data show that -cell Ca2+ER release and Sst secretion are amplified by glucose-induced allosteric activation of -cell Ca2+-sens- ing receptors (CaSRs). Finally, our preliminary data provide the first evidence that diabetic conditions diminish -cell Ca2+ER storage, which contributes to perturbations in glucose-stimulated Ca2+ handling and Sst secretion under diabetic conditions. Based on these exciting preliminary data, the overall objective of this proposal is to elucidate how -cell Ca2+ER is controlled and becomes disrupted during the pathogenesis of diabetes. This project will test the central hypothesis that glucose-stimulated -cell Sst secretion is amplified by CaSR-mediated Ca2+ER release, which is controlled by TALK-1 channel constraint of Ca2+ER storage. The rationale that underlies this project is that understanding how CaSR and TALK-1 control -cell Ca2+ER handling and Sst secretion will expose novel therapeutic targets for restoring glucose-stimulated Sst secretion and islet hormone secretion in T2D. This project will be accomplished with the following two specific aims: 1) Determine how -cell CaSR controls Ca2+ER handling, Sst secretion, and islet hormone secretion; and 2) Determine how TALK-1 channel control of Ca2+ER release modulates -cell function and dysfunction. Under the first aim, transgenic mice with -cell ablation of CaSR as well as human pseudoislets with ShRNA knockdown of -cell CaSR will be utilized to assess the roles of the Ca2+-sensing receptor during secretagogue modulation of -cell Ca2+ handling and Sst secretion. Aim1 will also determine how depletion of -cell Ca2+ER stores under diabetic conditions impacts CaSR signaling and Sst secretion. Under the second aim, the function TALK-1 channels on -cell Ca2+ER handling and function will be determined in mice with -cell specific ablation of TALK-1 and in human pseudoislets containing either -cells with knockdown of TALK-1 or expressing dominant negative TALK-1 channel subunits. Furthermore, Aim2 will determine how TALK-1 augmentation of -cell Ca2+ER depletion under the stressful conditions associated with diabetes contributes to -cell dysfunction. This project is significant because it is expected to illuminate mecha- nisms that alter -cell Ca2+ER handling and disrupt islet hormone secretion in T2D. Moreover, this project will identify pharmacological strategies for normalizing Sst secretion and reducing islet dysfunction in T2D.

项目摘要 2型糖尿病患者（T2D）和动物中的葡萄糖刺激的生长抑素（SST）分泌失去 该疾病的模型有助于破坏臀肌和胰岛素分泌。普遍接受 从细胞分泌的SST分泌是响应升高的细胞内Ca2+而发生的，这主要是由 内质网（ER）Ca2+（Ca2+ ER）释放。但是，控制细胞CA2+ER处理的机制 T2D中如何改变它们是未知的。来自我们实验室的数据发现，富含胰岛的两孔 - 域K+通道Talk-1是一个ER局部通道，在该通道中为细胞CA2+ ER释放提供了反流 和CA2+ER泄漏。 Talk-1介导的电化学驱动力的增强Ca2+ER泄漏的增加 菌株Ca2+ER存储，它限制了葡萄糖刺激的Ca2+ER释放和SST分泌。进一步的数据表明 细胞Ca2+ER释放和SST分泌通过葡萄糖诱导的细胞Ca2+-sens-的变构激活扩大 ING受体（CASR）。最后，我们的初步数据提供了第一个证据，表明糖尿病状况会减少 细胞CA2+ ER存储，这有助于葡萄糖刺激的Ca2+处理和SST分泌 在糖尿病状况下。基于这些令人兴奋的初步数据，该提案的总体目标是 阐明如何控制细胞Ca2+ER，并在糖尿病发病机理期间被破坏。这个项目 将测试中心假设，即葡萄糖刺激的细胞SST分泌被CASR介导的Ca2+ER扩增 释放，由CA2+ER存储的Talk-1通道约束控制。这是基础的理由 项目是了解CASR和Talk-1 Control如何如何处理CA2+ER处理和SST分泌 用于恢复T2D中葡萄糖刺激的SST分泌和胰岛Horsene分泌的新型热目标。这 项目将通过以下两个具体目标完成：1）确定细胞CASR如何控制Ca2+Er 处理，SST分泌物和胰岛式牛卷； 2）确定CA2+ER的Talk-1通道控制如何 释放调制细胞函数和功能障碍。在第一个目标下，具有细胞消融的转基因小鼠 CASR以及具有shrna of shrna细胞CASR的人类伪书将用于评估角色 细胞Ca2+处理和SST分泌过程中的Ca2+传感器受体的。 AIM1将 还可以确定糖尿病条件下的细胞Ca2+ER存储的耗竭如何影响CASR信号和SST 分泌。在第二个目标下，细胞Ca2+ER处理和功能的函数Talk-1通道将是 在用细胞特异性消融的小鼠中确定talk-1和人类伪符中的小鼠 通过敲除Talk-1或表达主导的负面谈话1频道亚基。此外，AIM2将 确定在与之相关的压力条件下如何扩展细胞Ca2+er部署 糖尿病会导致细胞功能障碍。该项目很重要，因为预计将阐明机甲 - 改变t2d中的细胞Ca2+ER处理和破坏胰岛质量的nisms。而且，这个项目将 确定在T2D中标准化SST分泌和减少胰岛功能障碍的药物策略。